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Centrifugal pumps have what advantage（s）over reciprocating pumps ________．
A.They are less expensive
B.They are smaller for equivalent pumping ability
C.They pump more cargo in less time
D.All of the above
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更多 “ Centrifugal pumps have what advantage（s）over reciprocating pumps ________．A.They are less expensiveB.They are smaller for equivalent pumping abilityC.They pump more cargo in less timeD.All of the above ” 相关考题
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What is the function of wearing rings found on some centrifugal pumps ________．A.Absorb erosion of high velocity discharge streamB.Seal pump shaft against entry of airC.Isolate the outlet side from the inlet sideD.Dampen the turbulent discharge flow
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What is a requirement for remote manual shutdown stations for internal combustion engine driven cargo pumps on tank barges ________．A.They must be conspicuously markedB.They must be located at least 10 feet from the engineC.There must be at least two such shutdown devicesD.The valve rods shall be fitted with stuffing boxes
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What is an advantage of diesel over steam turbine propulsion ________．A.Less fuel consumption per SHPB.Diesel fuel costs less than bunker C or its equivalentC.Less routine maintenance requiredD.Less weight per SHP
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单选题Mechanical lubricators for diesel engine cylinders are usually small reciprocating pumps which are （）.A
operated manually once an hourB
operated until the engine has startedC
placed into operation only at maximum loadD
adjustable to meet lubrication requirements
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单选题What is a function of the wearing rings used in most centrifugal pumps?（）A
Absorb erosion of high velocity discharge streamB
Seal pump shaft against entry of airC
Isolate the discharge side from the suction sideD
Dampen the turbulent discharge flow
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单选题Which of the following statements represents the advantage of rotary pumps as compared to reciprocating pumps?（）A
The high discharge pressure of the rotary pumps permits a larger volume of fluid per unit time than the reciprocating pumpB
Rotary pumps are capable of pumping more fluid than reciprocating pumps of the same weightC
Rotary pumps occupy only one-half the space of reciprocating pumpsD
Rotary pumps eliminate discharge slippage of the pumped liquid, while this does not hold true for a reciprocating pump
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单选题Which of the following pumps are self-priming, and can deal with liquid from a level below the pump? （） (1) reciprocating (2) rotary (3) centrifugalA
（1）onlyB
（1）and（2）C
（1），（2）and（3）D
（2）and（3）
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单选题The pumps employed on board ship can be divided into two main categories ie（） pumps and centrifugal pumps.A
gearB
nonpositive displacementC
positive displacementD
rotary
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单选题Air chambers are usually fitted to reciprocating pumps in order to （）.A
increase discharge pressureB
increase suction vacuumC
develop pulsation flowD
keep a steady rate of flow
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单选题What is a characteristic of all centrifugal cargo pumps? （）A
They are self-primingB
Decreasing the speed of rotation will decrease the discharge pressureC
Opening the discharge valve wider will increase the discharge pressureD
All of the above
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单选题A reciprocating pump belongs to （） according to its working principle.A
injector pumpsB
positive displacement pumpsC
centrifugal pumpD
centripetal pumps
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单选题Centrifugal pumps have what advantage(s) over reciprocating pumps?（）.A
They are less expensiveB
They are smaller for equivalent pumping abilityC
They pump more cargo in less timeD
All of the above
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单选题What is an advantage of diesel over steam turbine propulsion? （）A
Less fuel consumption per SHPB
Diesel fuel costs less than bunker C or its equivalentC
Less routine maintenance requiredD
Less weight per SHP
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单选题Under centrifugal pumps are the volute, diffuser, mixed-flow, axial flow and （） or regenerative types.A
reciprocatingB
hydraulicC
turbineD
vane
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单选题机舱人员应启动机舱里的消防泵。（）A
Engine room persons should stop their pumps in machinery space.B
Engine room persons should start their pumps in machinery space.C
Engine room persons should start their pumps in officer’s cabin.D
Engine room persons should start their pumps on boat deck.
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单选题Lube oil pumps taking suction from the sump of most small marine engines are usually （）.A
of the diaphragm typeB
of the centrifugal typeC
of the positive displacement typeD
independently driven by electric motors
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单选题The injection may be delayed, （）the pumps are in good order, if the fuel lines to the injection valves have not been cleared of air.A
becauseB
thoughC
sinceD
until
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单选题When installed for bilge pumping or ballast duty, centrifugal pumps require a （） to remove air from the suction pipe.A
air chamberB
head lankC
primerD
prime mover
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单选题Which of the following pumps belongs to centrifugal pump?（）A
Piston pumpB
Screw pumpC
Diffuser pumpD
Water-ring pump
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单选题Which of the materials listed is used as the dynamic seal material on mechanical seals installed on most centrifugal pumps used in water service?（）A
CopperB
Copper and carbonC
CarbonD
Bronze
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单选题The advantage of a centrifugal pump as compared with a reciprocating pump is that （）.A
discharge is continuousB
it has no internal valvesC
upon accidental closing of discharge valve, excessive pressure will not build upD
all of the above are true
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单选题Centrifugal pumps, however, can be designed with a number of impellers （） to attain a large amount of liquid.A
in seriesB
in parallelC
assembledD
together
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单选题Which of the following statements concerning the lubrication of diesel propulsion engines used in vessels over 300 gross tons is most accurate?（）A
Lubrication systems using engine driven lube oil pumps do not require any additional independent arrangement when such arrangements have been proven reliableB
The use of engine driven pre-lube pumps is permitted on vessels with propulsion systems developing less than 500 shaft horsepowerC
When forced lubrication is used for propulsion engines, one independently driven stand-by pumps is to be provided in addition to the necessary pumps for normal operationD
Lubrication systems where two oil coolers are fitted require a minimum of two temperature control devices which may be actuated by similar sensors
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单选题Fuel oil transfer systems used onboard diesel propelled vessels are required to have （）.A
two fuel oil transfer pumps provided where one is to be independent of the main engineB
two fuel oil transfer pumps, with a combined capacity exceeding the maximum consumption of the main engineC
engine driven transfer pumps and only used in constant speed applicationsD
the capacity of the engine driven pump exceed the consumption rate of the engine to which it is attached
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